J|$^ ON THE 0.XIDE1 P.F IRON. 



e. Fig. 3. A piece of wood torn oif the branch, showing the 

 ilpi»'or obstruction jubt below the pith. 



.V ,^ig. 4. A piece of wood cut lengthwise, with several, 

 buds, ric?, travelling from the line of life to the exterior, 

 through the wood; ee^ buds travelling through in another 

 direction ; ff, the new wood, or albumen. 



IV. 



Observations on the Oxides oj" Iron, with a Discussion o^their 

 Nature, By Mr. J. H. Hassenfratz. 



^Concluded from p. 1Q3,J 



Fi FTH Method. Oxidation of Iron by acids. 



j'onbya'cids W E know that iron is oxided when dissolved in acids, 

 1st, from the gas that is evolved ; and 2dly, from the nature 

 and state of the precipitates after the solution. We will ex- 

 amine, by each of these two methods separately, what pro- 

 portion of oxigen combines with the iron, to promote its 

 soiution, 



0/ the quantity of oxigen deduced from that of the gas 



evolved during the solution. 



CaTculation of According to the nature of the acids the gasses collected 



ihe oxigen will be different. When the iron is dissolved in nitric acid, 

 from the gas i . , > . . • • i > 



evolved. the acid itself is decomposed, its oxigen unites with the 



metal, and the nitrous gas, that was combined with it, is 

 evolved. In concentrated sulphuric acid too, the acid is 

 decomposed, and sulphurous acid is disengaged : but in 

 sulphuric acid diluted with water, muriatic acid, acetic acid, 

 fcc, it is the water that is decomposed, and hidrogen gas is 

 obtained. 

 l.avoisJer with Lavoisier dissolved iron in nitric acid, collecting and mea- 

 naricacid. spring the nitrous gas evolved*. Having ascertained bypre- 

 vious experiments the quantity of oxigen, with which this 

 gas must be combined to form nitric acid, he thence de- 

 duced the quantity combined with the iron during its solu- 

 tion. He found, that the results were very variable ; and 



» M€m. de V Ac. des Sc. 1782, p. 402 and following. 



that 



